Simulation of Pitting Corrosion Under Stress Based on Cellular Automata and Finite Element Method

Abstract A new cellular automaton (CA) program was written in Python language to simulate the random pitting evolution process, which can not only obtain a variety of different corrosion products but also obtain a variety of common corrosion morphologies on the surface of metal pipes, bridge steel members, etc. In addition, commercial finite element (FE) software ABAQUS was redeveloped using Python scripting language, and the FE mesh with the same size as the cellular mesh was established based on the consistent mesh algorithm, which ensured the efficiency and accuracy of the cyclic iterative algorithm. The stress and strain fields were calculated in real-time by applying the force load, the dissolution probability parameter P was updated in Python according to the force-chemical coupling model, and a new corrosion morphology was obtained in Python. At the same time, the birth and death element method was applied in ABAQUS to kill the corrosion elements in this iterative step simultaneously, and the new stress-strain field was recalculated in ABAQUS. The established consistent grid modeling strategy and cyclic iterative algorithm can significantly improve the solving efficiency of pitting evolution under the coupled action of corrosive medium and load. The results show that the stress concentration caused by pit expansion and the corrosion acceleration effect dominated by plastic deformation will promote each other, leading to the continuous growth of pitted pits. The established modeling strategy and cyclic iterative algorithm can significantly improve the solving efficiency of pitting evolution under the coupled action of corrosive medium and load.